In recent years, attention has been paid to a titanium oxide having a monoclinic β-type structure as an active material for a nonaqueous electrolyte battery.
Regarding a lithium titanate having a spinel structure (Li4Ti5O12), which has been hitherto put into practical use, the number of lithium ions that can be intercalated and eliminated per unit chemical formula thereof is three. For this reason, the number of lithium ions that can be intercalated and eliminated per titanium ion is theoretically 3.5, or 0.6, at most.
In the meantime, regarding a titanium oxide having a monoclinic β-type structure, the number of lithium ions that can be intercalated and eliminated per titanium ion is 1.0 at most, and thus the titanium oxide has a high theoretical capacity of about 335 mAh/g. It has been expected, accordingly, to develop a battery with an excellent performance using a titanium oxide having a monoclinic β-type structure.